SAD Syndrome and Lighting

SAD is an acronym for "seasonal affective disorder," a condition that occurs most often in fall and winter months when the daylight hours become short. The prevailing theory is that a lack of sunlight during these months causes depression and other health problems in some people.

Symptoms and Risk Factors

• The disorder can include such symptoms as depression, oversleeping, anxiety, weight gain, appetite changes, concentration problems and fatigue. Patients often report that their moods worsen during cloudy days. Risk factors include living a long distance from the equator, where yearly daylight is much shorter, and genetic factors showing a family history of depression.

Causes

• No consensus exists for SAD causes. One possibility is low serotonin levels resulting from a lack of light coming from the optic nerve to the brain. Another possible cause is a malfunction of the body's internal clock that regulates sleeping and waking, which is a fairly common problem among overnight and shift-rotation workers.

Treatments

• Treatments include light therapy, where the patient gazes into a special box designed to emit bright light. A light-emitting visor worn on the head is another option. Either method should be applied for approximately 30 minutes each day. Antidepressant medications are prescribed in some cases when light therapy isn't enough to help the patient.